1. Field of the Invention
The present invention relates to a pedal device used in a motor vehicle and having the function of disengaging a pedal supporting shaft from a pedal bracket at the time of a frontal collision of the vehicle.
2. Description of the Related Art
Many of automobiles (motor vehicles) are equipped with a suspended pedal device under the dash panel to allow the driver to operate the pedal device when braking or accelerating the vehicle. In many cases, the pedal device is constructed in such a manner that a supporting shaft to which a pedal arm is fastened is rotatably supported by a pedal bracket fixed to the dash panel, to allow the pedal arm to be suspended from the supporting shaft.
As such suspended pedal devices, a pedal device has been known in which, in order to ensure safety at the time of a frontal collision of the vehicle, the pedal arm is caused to disengage from the dash panel when an impact load exceeding a predetermined value is applied to the front of the vehicle during the frontal collision. Japanese Laid-open Patent Publication No. 2001-219828, for example, discloses a pedal device in which the pedal bracket is constituted by a fixed bracket secured to the dash panel and a separable bracket detachably coupled to the fixed bracket and supporting the supporting shaft. In this pedal device, when the dash panel is displaced toward the rear of the vehicle at the time of a frontal collision, the separable bracket is detached from the fixed bracket and thus from the dash panel to disengage the pedal.
Also, recently, a pedal device has been proposed in which at the time of a frontal collision, one end portion of the supporting shaft is disengaged from the pedal bracket secured to the dash panel, to allow the pedal arm to disengage while avoiding interference with devices attached to the pedal bracket or arranged around the pedal device.
Meanwhile, a pedal stroke sensor for detecting a swing of the pedal is often used with the pedal device, and techniques of electrically controlling devices on the basis of a detection signal from the pedal stroke sensor have been advanced. In electric vehicles and hybrid vehicles, for example, such a pedal stroke sensor is used to detect a swing of the brake pedal for operating a hydraulic brake apparatus, and a regenerative brake control apparatus is controlled in accordance with the pedal swing angle detected by the pedal stroke sensor, to achieve coordinated operation of the two apparatuses.
In many cases, the pedal stroke sensor is arranged near the pedal in such a manner that the axis of rotation of the pedal stroke sensor is aligned with that of the pedal, as disclosed in Japanese Laid-open Patent Publication No. 03-67315. The pedal stroke sensor has an input part engaged with the pedal so that the swing of the pedal may be transmitted to the pedal stroke sensor.
However, since numerous devices are arranged on the dashboard which is located in front of the driver's feet and to which the pedal device is attached, it is often very difficult to arrange the pedal stroke sensor in the close vicinity of the pedal.
In such cases, the pedal stroke sensor is attached to a portion of the bracket located at a distance from the pedal and is connected to the remote pedal by a transmission mechanism so that a swing of the pedal may be transmitted to the remote pedal stroke sensor through the transmission mechanism.
Also in the aforementioned pedal device which is configured to disengage one end portion of the supporting shaft, the pedal stroke sensor occasionally has to be arranged at a distance from the pedal because of various constraints. In such cases, a transmission mechanism is similarly used to transmit a swing of the pedal to the pedal stroke sensor.
In the case of the pedal device in which the bracket is allowed to be detached from the dash panel, like the one disclosed in Japanese Laid-open Patent Publication No. 2001-219828, the transmission mechanism connects the pedal stroke sensor arranged on the bracket, which is detached from the dash panel, to the pedal which also is detached from the dash panel. Accordingly, the transmission mechanism itself does not affect the disengagement of the pedal. In the case of the pedal device configured to disengage one end portion of the supporting shaft, however, the transmission mechanism connects the pedal stroke sensor, which is arranged on the pedal bracket fixed to the dash panel, to the pedal which is allowed to disengage from the pedal bracket. Thus, the transmission mechanism inevitably affects the disengaging movement of the pedal. Specifically, the individual parts of the transmission mechanism are so configured as to be movable only in their respective prespecified directions. Namely, although the transmission mechanism is capable of transmitting a swing of the pedal, it is unable to follow up change in the relative position between the pedal bracket and the pedal caused when the pedal supporting shaft disengages from the pedal bracket. As a result, the transmission mechanism hinders the disengaging movement of the supporting shaft from the pedal bracket. Thus, in the case of the pedal device configured to disengage one end portion of the supporting shaft from the pedal bracket, it is difficult to secure the pedal disengaging function where the pedal stroke sensor is arranged at a distance from the pedal.